This invention is based on the preamble of claim 1 of U.S. Patent Document U.S. Pat. No. 4,684,267.
This known device, which can be used for several bearing arrangements of a crankcase of a piston engine, serves the purpose of a step-by-step fracture separating of the bearing covers which are cast in one piece with the crankcase. For this purpose, this known fracture separating device comprises a cylindrical supporting body which can be introduced into the bearing bore of several bearing arrangements and has transversely directed cuts provided in the spacing of the bearing arrangements with respect to the respective guided arrangement of a separating element designed approximately in the shape of half a disk. Recesses in the supporting body and the separating elements, which are provided in the center in the longitudinal course, are used for receiving an operating rod for the separating elements. The operating rod, which is operatively connected with an energy accumulator, has wedge surfaces assigned to the separating elements for the radial displacement of the separating elements in the bearing bores for generating fracture separating forces.
This known device, which comprises a guidance of each separating element which is separate from the operating rod, has the disadvantage of a proportion of frictional force which is high relative to the sum of all fracture separating forces and which, in addition to the energy accumulator with correspondingly large dimensions, also results in high expenditures with respect to energy. The frictional forces in the known device, which are in effect on the wedge surface pairs of the operating rod and the separating elements, also result in a wear of a varying distribution which acts against an advantageous, virtually one-step breaking operation in the case of each bearing cover. On the contrary, this results in a time-staggered breaking of the bearing covers with resulting fracture separating surfaces of varying qualities because, for later-breaking bearing covers, the unchanged total fracture separating force is distributed to a few residual bearing covers. Furthermore, in the case of this known fracture separating process, the bearing covers are first fracture-separated from the crankcase on one side, specifically in an uncontrolled manner, and, for the fracture separating, for avoiding a bending breakage, the fracture-separated side of each bearing cover is rotationally secured by high-expenditure additional measures, for example, by means of screws.
A device for fracture-separating bearing covers with a relatively favorable ratio of the proportion of the frictional force of the device to the fracture separating force to be applied is known from European Patent Document EP-B 0 396 797. In the case of this device used for the fracture separating of connecting-rod bearing covers, the operating linkage is a falling impact mass for affecting a guided carriage on which a half-mandrel is arranged which penetrates the bearing covers of the rotationally secured connecting rod and is fixedly connected with the carriage on both ends. In this case, the guided carriage is used for guiding the half-mandrel affecting the bearing cover for the purpose of fracture separating.
In the case of this device with a guidance of the fracture-separating-effective half-mandrel, it is also a disadvantage that the impact mass acting as the operating linkage springs back because of the material elasticities when impacting on the pushed carriage used for guiding the half-mandrel, and therefore, during the fracture separating operation, the impact mass and the carriage do not constantly act in the same direction. In a disadvantageous manner, fracture surfaces of formed cracks may strike on one another in a swinging manner and cause a breaking-out of materials.
Finally, another device is known from U.S. Patent Document U.S. Pat. No. 4,754,906 which is used for the fracture separating of a connecting rod bearing cover and has a guidance for a fracture-separating-effective half-mandrel which is separate from the operating linkage. This half-mandrel, which is arranged in a relatively movable manner in a stand, is acted upon hydraulically. It comprises a chamber for a hydraulic operating linkage in which a piston-type extension, which is supported against a half-mandrel fixedly arranged on the stand, engages as a support of a sealing device.
The relatively massive, fracture-separating-effective half-mandrel is guided on the stand side by way of guiding surfaces spaced away from the piston-type chamber extension or from the plane of the introduction of the fracture separating force. Particularly as the wear of the guiding surfaces increases, this arrangement seems critical because, during the force-controlled impacting of the half-mandrel against the bearing bore of a connecting rod bearing arrangement, an oblique positioning cannot be excluded with results in additional friction. However, an oblique positioning has a disadvantageous effect on the fracture separating.
It is an object of the invention to design a device for fracture separating such that a relatively low proportion of friction force remains low for a long usage time of the device as a result of a simpler structure of the device and such that the device structure permits a desired massive construction of the device, while the space requirements are relatively low, for a force which can be abruptly set free from a respective energy accumulator and which, acting as an active force directly on the bearing cover to be separated, is intended for a perfect one-step fracture separating of a bearing cover which is held in a rotationally secured manner by means of the device.
This object is achieved by means of claim 1, the inventive design of the device for fracture separating being characterized in that, for the fracture separating, a half-mandrel or full mandrel which can be axially arranged in one or several bearing bores is provided, and in that an operating linkage, which exclusively causes the guiding of the respective mandrel in the fracture separating direction, is applied to the respective mandrel transversely to its longitudinal course, in which case the corresponding mandrel is held in a rotationally secured manner and each bearing cover is rotationally secured while being clamped against the respective mandrel.
The inventive combination of the characterizing features advantageously results in a simpler structure of the device, in which case, in comparison to the prior art, the simpler structure, in a manner which is significant with respect to the invention, is achieved by means of a combined operating/guiding linkage which is applied to the respective mandrel transversely with respect to its longitudinal course in the fracture separating direction. By means of the integration according to the invention of the mandrel guidance required for a perfect fracture separating with the operating linkage, the number of guiding surfaces subjected to friction is considerably reduced. The advantage is a frictional force proportion to be generated by the energy accumulator which is lower relative to the fracture separating force. This has the additional advantage of a smaller-size energy accumulator and, because of the lower friction loss for an abrupt introduction of force, advantageously results in an almost vertical course of the rise of force in the case of a corresponding selection of an energy accumulator.
By means of the selection of an energy accumulator in the preferred construction of a piston cylinder-unit with a piston rod which forms a section of the operating linkage, in a further advantageous manner, a simple construction of the structure of the invention is achieved in that the piston rod which is guided in a straight manner on the cylinder side is used for the straight guiding of the respective mandrel in the fracture separating direction. This fracture separating device which, in comparison to the prior art, according to the invention, has a minimum of guiding surfaces with respect to its structure, irrespective of the number of the bearing covers to be fracture-separated, in addition to having a simple construction, it can be designed to be advantageously massive for a one-step fracture separating.
A particularly massively constructed operating linkage can advantageously be used for the rotationally securing arrangement of the respective fracture separating mandrel. In a further advantageous manner, the massively designed operating linkage permits the arrangement of a clamping device for a bearing cover which is operated in a controlled manner, in which case the clamping device is brought to rest against the assigned bearing cover before the fracture separating in such a manner that the bearing cover is clamped in a rotationally secured manner between the clamping device and the respective fracture separating mandrel during and after the fracture separating in order to avoid a bending fracture in a last-breaking separating area.
The combined operating/guiding linkage which is guided in a straight manner and has a fracture separating mandrel which is rotationally secured relative to the operating/guiding linkage and has bearing covers which can be clamped in a rotationally secured manner relative to the fracture separating mandrel, is therefore advantageously distinguished by the avoidance of influences which, in the operation of the device may be disadvantageous for the one-step fracture separating (oblique positioning, large plays, elasticities of materials).
In addition to the preferred piston-cylinder unit, falling weights are conceivable as energy accumulators for triggering the fracture in the case of a corresponding prestressing force, and furthermore, a modified operating linkage with a kinematically separately caused straight guidance of its connection point with the respective fracture separating mandrel is also conceivable.
For a fracture separating device, which is massively structured while its construction is compact, a hydraulic piston-cylinder unit is preferred as an energy accumulator by means of which a desirably high prestressing force and, by means of a hydraulic intensification, a fracture separating force which can be set free abruptly can by implemented.
Advantageous embodiments of the invention are described in additional subclaims. In particular, these describe fracture separating mandrels which are designed with a view to different possibilities of introducing the reaction force, which is diametrical to the fracture separating force, into the respective machine member, and fracture separating devices which by means of these mandrels are in each case adapted with respect to the construction and the arrangement. Additional subclaims relate to applications of the fracture separating devices according to the invention with respect to the number and arrangement of several bearing covers to be separated, also with respect to relative arrangements of fracture separating surfaces of a bearing cover and finally with respect to the handling of fracture-separated bearing covers of one or several machine members.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.